1. Field of the Invention
This invention relates generally to bowling balls and more particularly to bowling balls including means for regulating the balance and axial moments of the bowling ball to compensate for finger grip holes.
2. Background Art
Bowling or ten pins has been practiced as a sport for well over a century. More recently, bowling has attained a status as a professional sport. Together with that status and with the popularity of the sport, rules and regulations have been established and promulgated which provide exacting standards for professional play. Everything from the width and length of the bowling lane to the size, shape, weight and composition of the bowling ball must meet specific regulations promulgated by the American Bowling Congress (ABC) in order for play to be recognized as meeting tournament standards.
The ABC rules prohibit the introduction into a bowling ball of metal or any other substance which is not comparable to the original material used in manufacturing a bowling ball. Further, the rules require that a bowling ball be constructed without voids in its interior, that the ball be of a nonmetallic composition material, and that the ball conform to specified weight, size and balance.
A bowling ball includes means for a bowler to hold the ball with one hand. Finger grip holes drilled into the bowling ball provide a grip means, using a configuration having either two finger grip holes or three finger grip holes. Because each bowler's hand measurements are generally different from the measurements of other bowlers, there is a wide range of dimensions in finger grip hole diameter, the depths to which the holes are drilled, and their location relative to each other. The finger grip holes create a void in the bowling ball which must be compensated in order to avoid excessive imbalance in the bowling ball.
A counterweight made from a material which has a higher density than the material comprising the remainder of the bowling ball body has been used to compensate for material drilled out of the bowling ball body to form the finger grip holes. However, the broad variety of individual bowlers' measurements leads to differences in the weight and positioning of the counterweights required.
Prior art attempts to compensate for the material drilled out of the finger holes have been constrained by an inability to provide a high density, nonmetallic counterweight. U.S. Pat. No. 4,121,828 discloses a bowling ball in which the core is composed of two different materials. One material, forming the main mass of the core body, is either plastic or an elastomeric rubberlike material. The other material, also made of plastic or rubberlike material, is embedded within the material comprising the main body of the core. The second material is greater in density than the first material. The bowling ball also is encapsulated by an external shell. The position and orientation of the embedded material is marked so that finger holes drilled into the bowling ball match the counterweight made from the heavier density material embedded in the core.
Because the materials of the core comprise similar plastic or rubberlike materials, the difference in density between them and generally results from a difference in the number of carbon atoms in the elastomeric materials forming the different core materials. Accordingly, the difference in density of the two materials is not great and a substantial quantity of the embedded material is required to compensate for the material drilled out of the finger grip holes.
Moreover, the need to provide two different materials in exacting predetermined ratios requires unnecessarily complex fabricating and indexing procedures to provide proper balance and orientation of the finger grip holes relative to the high density material embedded in the core. Another prior art attempt at solving the problem of bowling ball balance is disclosed in U.S. Pat. No. 3,441,274. That construction contemplates the use of removable plugs to offset weight imbalances created in the normal manufacturing process of the bowling ball. The removal of these plugs creates voids in the body of the bowling ball, voids which are not permitted under tournament regulations. Each of the prior art devices lacks an easily indexed, precisely positionable counterweight means that can adequately and easily compensate for the material which is drilled out of a bowling ball in forming the finger grip holes.